From what I've seen here in the past about such topics, usually around no further out then about a week and a half.  a lot of things can happen in a week so any longer might be taking a risk for a last minute let-down. Always have a back-up plan in case that happens.

Since you don't have any reviews, I'm not sure what the response will be. You're p 411, so that's a good thing. Write a well thought out intelligent iso request. Admit that you don't have reviews, but you're willing to work on screening requests. Tell the ladies what you like, milf, spinner, gfe, pse, incall, outcall you know what I mean. There are many fantastic ladies in Phoenix, I live there. Check my reviews for an idea. Many ladies welcome planning in advance, but your lack of reviews probably have the ladies being lackadaisical. ,  Good luck,

a certain day/night, approximate time, length of appointment, etc.  General e-mail like "Hey Sweetie, I'm going to be in Phoenix the week of Dec. 8, want to see me?" will not get a response.  Like has been said previously, you might want to have a plan B in case something falls through.

Some ladies operate in a "call me to check availability and I'll see you in 30 min" and some operate in a "let's plan ahead" way.  It's not always easy to tell which is which... though the more screening a lady does and the higher her price point is *usually* is an indicator.

Personally, I love planning ahead.  I have a busy life outside this demimonde and only have limited availability for play.  I also tend to book out 3-6 weeks in advance, have a higher minimum and screen more than most.  I happen to *love* the gent who inquires 4+ weeks in advance and supplies the requisite screening info (and a bit about him as a human being) as well as specifics as to his desired date/time in the initial inquiry - but I do respond to all inquiries regardless.  

I happen to view a non-response to a *detailed* inquiry as a sign of how the lady runs her business.... and there are some gorgeous, well-reviewed ladies out there who would never be able to earn my business (yes, I do book other ladies for myself alone- or to join myself and a particular friend) simply because of how lackadaisically they run their businesses.  It leaves a bad taste in my mouth (no pun intended).   Understandably, there can also be legitimate reasons why a particular lady cannot return your email as quickly as you'd like.... but to have all of them be unresponsive?

Unfortunately, I've heard similar stories of unresponsiveness (best one was contacting 13 P411 girls for a 1 week lead time request with all the pertinent details and having zero response by the time the week had elapsed). It saddens and "maddens" me...  My best advice to you is to choose more wisely!